1. Field of the Invention
The present invention relates to an electronic device with a built-in antenna, and more particularly to an electronic device built in with a self-complementary antenna (SCA).
2. Description of Related Art
An antenna is built in some notebook computers to allow the notebook computers to have the radio electromagnetic signal receiving function. There are many built-in notebook computer antennas, such as the ones disclosed in U.S. Pat. No. 6,995,718, U.S. Pat. No. 6,853,336, U.S. Pat. No. 6,833,818, U.S. Pat. No. 6,809,690, U.S. Pat. No. 6,724,348, U.S. Pat. No. 6,628,236, U.S. Pat. No. 5,828,341 and Taiwan Utility Model Patent No. M279,992 and M281,308. The antennas disclosed in the patents mentioned above almost are single-element-typed antennas, the electromagnetic signal transmission efficiency is rather low and the electromagnetic signal transmission bandwidth is rather narrow.
Taiwan Patent No. 595,041 discloses a similar self-complementary antenna. The antenna comprises a coaxial transmission line with a central wire and an outer layer grounding conductor, a first metal radiating sheet and a second metal radiating sheet, in which the shapes of the first and the second metal radiating sheets generally are complementary to each other. The both radiating sheets are formed on a medium base plate by means of printing or etching and disposed symmetrically on two sides of the medium base plate relative to a central line of the medium base plate to form two arms of the antenna. Besides, each of the both metal radiating sheet comprises a feeding point connected to a center wire or an outer layer grounding conductor of the coaxial transmission line. The antenna mentioned above has a rather wide bandwidth.